分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-04-25
摘要： A Laue microdiffraction beamline (BL03HB) was constructed at the Shanghai Synchrotron Radiation Facility (SSRF). This beamline features two consecutive focusing points in two different sectors within its end station, the first dedicated to protein crystallography and the other tailored to materials science applications. Based on a superbend dipole magnet with a magnetic field of 2.29 T, a two-stage focusing design was implemented with two sets of Kirkpatrick–Baez mirrors to achieve a micro white beam as small as 4.2×4.3 µm 2 at the first sector and 0.9×1.3 µm 2 at the second sector in the standard beamline operation mode at SSRF. The X-ray microbeam in the two sectors can be easily switched between monochromatic and white beams by moving a four-bounce monochromator in or out of the light path, respectively. In the protein crystallography sector, white-beam Laue microdiffraction was demonstrated to successfully determine the structure of protein crystals from only a few images of diffraction data collected by a Pilatus 2M area detector. In the materials science sector, the white-beam Laue diffraction was collected in a reflection geometry using another Pilatus 2M area detector, which could map the microstructural distribution on the sample surface by scanning the samples. In general,the BL03HB beamline promotes the application of Laue microdiffraction in both protein crystallography and materials science. This paper presents a comprehensive overview of the BL03HB beamline, end station, and the first commission results.
分类： 物理学 >> 核物理学 提交时间： 2022-06-13
摘要： Shanghai Laser Electron Gamma Source (SLEGS) is a powerful gamma source to provide MeV gamma-ray beams for nuclear science and technology. It is developed as one of the sixteenbeamline stations in Phase II Project of the Shanghai Synchrotron Radiation Facility (SSRF). Theslant-scattering mode is for the first time systematically employed in the laser Compton scattering (LCS) at SLEGS to produce energy-tunable quasi-monoenergetic gamma-ray beams. SLEGS officially completed its commissioning from July to December 2021. Gamma-rays in energy range of 0.25 - 21.7 MeV with the flux of 2.1 104 - 1.2 107 photons/s and the energy spread of 2 15 % are produced during the test. This paper reports results of the commissioning of the SLEGS beamline.
分类： 地球科学 >> 地理学 提交时间： 2021-07-23 合作期刊: 《干旱区科学》
摘要： Lop Sea, located at the east end of the Tarim Basin, Northwest China, dried up permanently, which is the terminal lake of the Tarim River. Lop Sea was considered as the lake basin of Lop Nor since Quaternary. However, the possibility that Lop Nor was away from the Lop Sea in historical time is crucial to be discussed to interpret the proxy records in sediment profiles. To obtain a general view of the evolution of Lop Nor and Lop Sea in a historical period, several approaches were adopted in this paper. First, the Qianlong Thirteen-Row Atlas, an ancient imperial atlas of the Qing Dynasty, which was completed around 1760, indicated that the Tarim River formed a relatively large lake at its modern upstream region. Second, a Digital Elevation Model (DEM) with a 10-m spatial resolution and a relative precision of 0.42 m was derived from TanDEM-X/TerraSAR-X satellite image pairs using the interferometry method, which was verified using ICESat-GLAS laser footprints and a local DEM acquired by a drone. Finally, based on the spatial analysis of historical documents, expedition reports, sediment profiles and archaeological evidence, it can be deduced that the lacustrine deposition was discontinued in the Lop Sea. Six episodes in the evolutionary history of the drainage system in eastern Tarim Basin were summarized. The proved depositional condition variations could be used for future interpretation of proxy records in sediment. The high-accurate DEM provided a reference for the location of further fieldwork in the Lop Sea. The method proposed in this paper may be efficient for the research of inland lakes or rivers in global arid regions.
分类： 物理学 >> 核物理学 提交时间： 2016-09-13
摘要： An S band SLED-type pulse compressor has been manufactured by IHEP to challenge the 100 MW maximum input power, which means the output peak power is about 500 MW at the phase reversal time. In order to deal with the RF breakdown problem, the dual side-wall coupling irises model was used. To further improve the reliability at very high power, amplitude modulation and phase modulation with flat-top output were taken into account. The RF modulation studies on an S-band SLED are presented in this paper. Furthermore, a method is developed by using the CST Microwave Studio transient solver to simulate the time response of the pulse compressor, which can be a verification of the modulate theory. In addition, the experimental setup was constructed and the flat-top output is obtained in the low power tests.
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